(a) Field of the Invention
The present invention relates to a method for controlling unidirectional link connection in a mobile ad hoc network, and a recording medium storing a program thereof. More specifically, the present invention relates to a method for controlling unidirectional link connection in a mobile ad hoc network, and a recording medium storing a program thereof for detecting unidirectional links generated by a transmission power difference, and providing connectivity of a unidirectional link to an upper layer.
(b) Description of the Related Art
Ad hoc networks represent networks with only mobile terminals, designed in the assumption that most wireless MAC (medium access control) protocols have identical transmission power at all mobile nodes.
However, the actual ad hoc network includes various devices categorized as battery-based personal portable devices, and devices that are supplied with optimal power from their power source. The personal portable devices include a notebook computer, a PDA, and a mobile phone, and the devices receiving optimal power include mobile communication devices attached to tanks, helicopters, armored motorcars, fire engines, and ambulances.
The devices have different transmission powers because of differences in power supplied to the devices and differences in size of the devices because of portability, which generates unidirectional links. Here, a unidirectional link may be generated between a high transmission power node and a low transmission power node, wherein data is only transmitted from the high transmission power node to the low transmission power node.
So as to utilize the unidirectional link, the low transmission power node conventionally senses the unidirectional link, and a frame that approaches a start mobile node of the unidirectional link is tunneled using a routing function of a network layer.
A method for sensing the unidirectional link according to prior art enables each mobile node to hold a neighbor node list of the neighboring nodes that are adjacent to the mobile node, load the neighboring node list into the ‘Hello’ message that is periodically broadcasted to adjacent neighboring nodes, and transmit the message to the adjacent neighboring nodes.
In this instance, when the ‘Hello’ message is transmitted between two mobile nodes in the unidirectional link relation, the neighboring node list in the ‘Hello’ message of the high transmission power node includes no low transmission power nodes.
Therefore, the low transmission power node is required to receive the ‘Hello’ message and detect a unidirectional link. The low transmission power node uses information collected by a routing protocol to tunnel an ACK of a link layer from an end point of the unidirectional link to the packet start point, and routing information of a network layer. Accordingly, the high transmission power node may transmit data using the unidirectional link.
As described above, since the prior art method for sensing the unidirectional link performs communication using the routing function of an upper layer, it delays frame transmission and generates processing overhead.